Mitigation State Verification Systems And Methods

ABSTRACT

A mitigation verification system includes: a control module configured to selectively transition a mitigation device of a refrigeration system of a building from a first state to a second state; and a verification module configured to verify and generate an indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state based on a change in a parameter of the refrigeration system over a period in response to the transition by the control module.

FIELD

The present disclosure relates to refrigerant leak mitigation and more particularly to systems and methods for verifying whether mitigation of a refrigerant leak is being performed.

BACKGROUND

The background description provided here is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.

Refrigeration and air conditioning applications are under increased regulatory pressure to reduce the global warming potential of the refrigerants they use. In order to use lower global warming potential refrigerants, the flammability of the refrigerants may increase.

Several refrigerants have been developed that are considered low global warming potential options, and they have an ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) classification as A2L, meaning mildly flammable. The UL (Underwriters Laboratory) 60335-2-40 standard, and similar standards, specifies a predetermined (M1) level for A2L (or mildly flammable) refrigerants and indicates that A2L refrigerant charge levels below the predetermined level do not require leak detection and mitigation.

SUMMARY

In a feature, a mitigation verification system includes: a control module configured to selectively transition a mitigation device of a refrigeration system of a building from a first state to a second state; and a verification module configured to verify and generate an indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state based on a change in a parameter of the refrigeration system over a period in response to the transition by the control module.

In further features, the first state is an OFF state and the second state is an ON state.

In further features, the first state is a first speed and the second state is a second speed.

In further features, the mitigation device is a blower configured to increase airflow past a heat exchanger of the refrigeration system within the building.

In further features, the parameter of the refrigeration system is a temperature of air in a duct within the building measured by a temperature sensor.

In further features, the parameter of the refrigeration system is a pressure of air in a duct within the building measured by a pressure sensor.

In further features, the parameter of the refrigeration system is a flowrate of air in a duct within the building measured by a flowrate sensor.

In further features, the parameter of the refrigeration system is a humidity of air in a duct within the building measured by a humidity sensor.

In further features, the parameter of the refrigeration system is a current to a motor of a blower configured to increase airflow past a heat exchanger of the refrigeration system within the building.

In a feature, a system includes: the mitigation verification system; and a refrigerant sensor configured to measure an amount of a refrigerant of the refrigerant system in air, where the verification module is configured to disable the refrigerant sensor when the mitigation device is in the ON state.

In further features, the refrigerant is classified as at least mildly flammable by at least one governing body.

In further features, the control module is configured to selectively transition the mitigation device from the first state to the second state when the amount of the amount of refrigerant of the refrigerant system in air is greater than a predetermined value.

In further features, the verification module is configured to generate the indicator that the mitigation device of the refrigeration system transitioned from the first state to the second state when a magnitude of the change in the parameter of the refrigeration system over the period is greater than a predetermined value.

In further features, a thresholds module is configured to set the predetermined value to a fixed predetermined value.

In further features, a thresholds module is configured to vary the predetermined value.

In further features, a thresholds module is configured to set the predetermined value based on an average of X values of the change measured in response to X transitions by the control module.

In further features, the verification module configured to verify and generate the indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state further based on a second change in a second parameter of the refrigeration system over a second period in response to the transition by the control module.

In further features, the verification module configured to verify and generate the indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state further based on a third change in a third parameter of the refrigeration system over a third period in response to the transition by the control module.

In a feature, a verification system includes: a control module configured to selectively transition a mitigation device of a refrigeration system of a building from a first state to a second state; and a verification module configured to: determine a change in a parameter of the refrigeration system over a predetermined period; determine whether the change is greater than a predetermined value associated with the mitigation device transitioning from the first stat to the second state; and update and indicate a present state of the mitigation device when the change is greater than the predetermined value.

In a feature, a verification method includes: selectively transitioning a mitigation device of a refrigeration system of a building from a first state to a second state; and verifying and generating an indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state based on a change in a parameter of the refrigeration system over a period in response to the transition by the control module.

Further areas of applicability of the present disclosure will become apparent from the detailed description, the claims and the drawings. The detailed description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a functional block diagram of an example refrigeration system;

FIG. 2 is a functional block diagram of an example portion of the refrigeration system of FIG. 1;

FIG. 3 is a functional block diagram of an example implementation of a control module;

FIGS. 4-9 are flowcharts depicting example methods of verifying and indicating whether a mitigation device transitioned from a first state to a second state;

FIG. 10 includes an example graph of pressure changes over time when a blower turned ON and OFF;

FIG. 11 includes an example graph of temperature changes over time when a blower turned ON and OFF;

FIGS. 12-13 are flowcharts depicting example methods of verifying and indicating whether a mitigation device transitioned from a first state to a second state; and

FIG. 14 is a flowchart depicting an example method of verifying the state of a mitigation device.

In the drawings, reference numbers may be reused to identify similar and/or identical elements.

DETAILED DESCRIPTION

Some refrigerants used in refrigeration systems may be classified as mildly flammable (e.g., A2L refrigerants) by one or more classification bodies, such as ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) and UL (Underwriters Laboratory). Refrigeration systems using mildly flammable refrigerant may include a refrigerant leak sensor configured to measure an amount of refrigerant that is present in air outside of the refrigeration system within a building served by the refrigeration system.

When a refrigerant leak occurs, a control module may turn on a mitigation device (e.g., a blower of the refrigerant system) to mitigate the refrigerant leak by dissipating the refrigerant. One or more other mitigation actions may additionally or alternatively be taken when a refrigerant leak occurs. If the blower (or other mitigation device) fails to turn on (or otherwise transition from a first state to a second state), mitigation of a refrigerant leak may be delayed or minimized.

The present application involves a control module determining and indicating whether a mitigation device (e.g., the blower) actually transitioned from a first state (e.g., OFF or a first speed) to a second state (e.g., ON or a second higher speed) in response to the control module attempting the transition. The control module determines and indicates whether the mitigation device transitioned based on a change in one or more operating parameters over a period in response to the attempt. Examples of the operating parameters include air temperature within a duct of the refrigeration system, air pressure within a duct of the refrigeration system, humidity within a duct of the refrigeration system, a gas flowrate (e.g., air) of the refrigeration system, a current, a voltage, a speed, a differential pressure, and gas (e.g., air) speed.

FIG. 1 is a functional block diagram of an example refrigeration system 100 including a compressor 102, a condenser 104, an expansion valve 106, and an evaporator 108. The refrigeration system 100 may include additional and/or alternative components, such as a reversing valve or a filter-drier. In addition, the present disclosure is applicable to other types of refrigeration systems including, but not limited to, heating, ventilating, and air conditioning (HVAC) systems, heat pump systems, and chiller systems. For example, the refrigeration system 100 may include a reversing valve (not shown) that is configured to reverse a direction of refrigerant flow in a heat pump system.

The compressor 102 receives refrigerant in vapor form and compresses the refrigerant. The compressor 102 provides pressurized refrigerant in vapor form to the condenser 104. The compressor 102 includes an electric motor that drives a pump. For example only, the pump of the compressor 102 may include a scroll compressor and/or a reciprocating compressor.

All or a portion of the pressurized refrigerant is converted into liquid form within the condenser 104. The condenser 104 transfers heat away from the refrigerant, thereby cooling the refrigerant. When the refrigerant vapor is cooled to a temperature that is less than a saturation temperature, the refrigerant transforms into a liquid (or liquefied) refrigerant. The condenser 104 may include an electric fan that increases the rate of heat transfer away from the refrigerant. The refrigerant may be classified as at least mildly flammable by one or more classification bodies, such as ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) and UL (Underwriters Laboratory). For example, the refrigerant may be classified as A2L or more flammable by ASHRAE.

The condenser 104 provides the refrigerant to the evaporator 108 via the expansion valve 106. The expansion valve 106 controls the flow rate at which the refrigerant is supplied to the evaporator 108. The expansion valve 106 may include a thermostatic expansion valve or may be controlled electronically by, for example, a control module 130. A pressure drop caused by the expansion valve 106 may cause a portion of the liquefied refrigerant to transform back into the vapor form. In this manner, the evaporator 108 may receive a mixture of refrigerant vapor and liquefied refrigerant.

The refrigerant absorbs heat in the evaporator 108. Liquid refrigerant transitions into vapor form when warmed to a temperature that is greater than the saturation temperature of the refrigerant. The evaporator 108 may include an electric fan that increases the rate of heat transfer to the refrigerant.

A utility 120 provides power to the refrigeration system 100. For example only, the utility 120 may provide single-phase alternating current (AC) power at approximately 230 Volts root mean squared (V_(RMS)). In other implementations, the utility 120 may provide three-phase AC power at approximately 400 V_(RMS), 480 V_(RMS), or 600 V_(RMS) at a line frequency of, for example, 50 or 60 Hz. When the three-phase AC power is nominally 600 V_(RMS), the actual available voltage of the power may be 575 V_(RMS).

The utility 120 may provide the AC power to the control module 130 via an AC line, which includes two or more conductors. The AC power may also be provided to a drive 132 via the AC line. The control module 130 controls the refrigeration system 100. For example only, the control module 130 may control the refrigeration system 100 based on user inputs and/or parameters measured by various sensors (not shown). The sensors may include pressure sensors, temperature sensors, current sensors, voltage sensors, etc. The sensors may also include feedback information from the drive control, such as motor currents or torque, over a serial data bus or other suitable data buses.

A user interface 134 provides user inputs to the control module 130. The user interface 134 may additionally or alternatively provide the user inputs directly to the drive 132. The user inputs may include, for example, a desired temperature, requests regarding operation of a fan (e.g., a request for continuous operation of the evaporator fan), and/or other suitable inputs. The user interface 134 may take the form of a thermostat, and some or all functions of the control module (including, for example, actuating a heat source) may be incorporated into the thermostat.

The control module 130 may control operation of the fan of the condenser 104, the fan of the evaporator 108, and the expansion valve 106. The control module 130 may also control actuation of the reversing valve.

The drive 132 may control the compressor 102 based on commands from the control module 130. For example only, the control module 130 may instruct the drive 132 to operate the motor of the compressor 102 at a certain speed or to operate the compressor 102 at a certain capacity. In various implementations, the drive 132 may also control the condenser fan.

The evaporator 108 may be located within a building served by the refrigeration system. The condenser 104 may be located outside of the building. In heat pump systems, the functions of the evaporator 108 and the condenser 104 are switched (via the reversing valve) depending on whether heating is to be performed within the building or cooling is to be performed within the building. When cooling is performed, the condenser 104 and the evaporator 108 perform as described above. When heating is performed, refrigerant flow is reversed, and the condenser 104 and the evaporator 108 operate oppositely. The condenser 104 and the evaporator 108 may therefore be more generally referred to as heat exchangers.

A refrigerant leak sensor 140 is disposed inside of the building and measures an amount (e.g., concentration) of refrigerant in air (outside of refrigerant channels in the refrigeration system) present at the refrigerant leak sensor. The refrigerant leak sensor 140 may be located, for example, near the evaporator 108, such as downstream of a blower that blows air across the evaporator 108 and into the building through ducts. The refrigerant leak sensor 140 may also be located downstream of evaporator 108.

The refrigerant leak sensor 140 generates a signal based on the amount of refrigerant measured. For example, the refrigerant leak sensor 140 may transmit the amount of refrigerant to the control module 130. Alternatively, the refrigerant leak sensor 140 may set the signal to a first state when the amount is greater than a predetermined amount and set the signal to a second state when the amount is less than the predetermined amount. The predetermined amount may be, for example, 25 percent of a lower flammability level of the refrigerant or another suitable value. In various implementations, the refrigerant is classified under one or more standards as being mildly flammable. For example only, the refrigerant may be classified as an A2L refrigerant or more generally mildly flammable as discussed above. The classification may be, for example, by a standard of ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), UL (Underwriters Laboratory) 60335-2-40 standard, or in another standard which may be by ASHRAE, UL, or another body.

The control module 130 receives the output of the refrigerant leak sensor 140 and determines whether a refrigerant leak is present based on the output. For example, the control module 130 may determine that a leak is present when the output is in the first state or when the amount is greater than the predetermined amount. If the amount is less than the predetermined amount or the output is in the second state, the control module 130 may determine that no leak is present.

One or more remedial actions may be taken when a refrigerant leak is present (e.g., the signal indicates that the amount is greater than the predetermined value or the signal is in the first state). For example, the control module 130 may turn on the blower (that blows air across the evaporator 108) when a refrigerant leak is present. Turning on the blower may disperse leaked refrigerant. Additionally, the control module 130 may turn off the compressor 102 and maintain the compressor 102 off until the leak is remediated (e.g., for a predetermined period). Additionally, the control module 130 may actuate one or more lockout devices to prevent ignition by one or more ignition devices within the building. Ignition by an ignition device may ignite leaked refrigerant.

Additionally or alternatively, the control module 130 may close one or more isolation valves to isolate the refrigerant outside of the building. In various implementations, a first isolation valve may be implemented directly between the condenser 104 and the expansion valve 106. The control module 130 may close the first isolation valve when a leak is detected. A second isolation valve may be implemented directly between the evaporator 108 and the compressor 102. The control module 130 may maintain the second isolation valve open while the compressor 102 is on and the first isolation valve is closed to pump refrigerant out from within the building. The control module 130 may close the second isolation valve after operation of the compressor 102 for a predetermined period with the first isolation valve closed.

Additionally or alternatively, the control module 130 may generate one or more indicators when a leak is present. For example, the control module 130 may transmit an indicator to one or more external devices, generate one or more visual indicators (e.g., turn on one or more lights, display information on one or more displays, etc.), and/or generate one or more audible indicators, such as via one or more speakers. The indicators may, for example, alert an occupant, owner, or service technician of the presence of a refrigerant leak.

The refrigerant leak sensor 140 may be, for example, non-dispersive infrared (NDIR) refrigerant sensor, a thermal conductivity refrigerant sensor, a quartz crystal microbalance (QCM) sensor, or another suitable type of refrigerant leak sensor. NDIR sensors include an infrared (IR) lamp that transmits light through a tube. A fan or blower may push or pull gas (e.g., air and, if a leak is present, refrigerant) through the tube. An optical sensor receives light from the IR lamp through the tube and measures the amount of refrigerant in the gas based on one or more characteristics of the light. A thermal conductivity sensor includes conductive plates between which the gas may be pushed or pulled by a blower or a fan. The blower or fan may be omitted in various implementations. Different amounts of refrigerant have different thermal conductivities. Thermal conductivity sensors include two temperature sensors (e.g., one before and one after a heating element). A thermal conductivity sensor determines a temperature difference between the measurements from the two sensors. Given a known heating input from the heating element, the thermal conductivity sensor determines the amount of the refrigerant based on the temperature difference. Different amounts of refrigerant have different densities and may therefore cause different vibrations. QCM sensors measure the amount of refrigerant in the gas based on the vibration. Other examples of refrigerant leak sensors 140 include metal oxide refrigerant sensors, acoustic refrigerant sensors, quartz resonation (e.g., QCM) refrigerant sensors, and carbon nanotube refrigerant sensors. Metal oxide refrigerant sensors measure a resistance across a surface oxidizer heated by a hotplate. In the presence of the refrigerant, the resistance of the oxidizing layer may decrease. As refrigerant dissipates, the resistance of the oxidizing layer may increase. A metal oxide refrigerant sensor may determine the amount of refrigerant based on the resistance.

As discussed above, the control module 130 turns on the blower when a refrigerant leak is detected. The present application involves verifying that the blower is on when the blower is to be on based on one or more operating parameters, for example, to ensure that remediation of a refrigerant leak is possible if a refrigerant leak occurs.

FIG. 2 is a functional block diagram of an example portion of the refrigeration system of FIG. 1. When on, a blower 204 draws air in from within the building through one or more return air ducts. The blower 204 forces air past the evaporator 108. The evaporator 108 transfers heat to or from the air as the air passes the evaporator 108. Heated or cooled air flows from the evaporator 108 to within the building through one or more supply air ducts.

One or more sensors may be implemented in addition to the refrigerant leak sensor 140. For example, a motor current sensor 208 may measure current to the blower 204 and more specifically to an electric motor of the blower 204. The control module 130 may determine that the blower 204 is on (and turn off the refrigerant leak sensor 140) when the current is greater than a predetermined current.

Additionally or alternatively, a voltage sensor 212 may measure a voltage applied to the electric motor of the blower 204. The control module 130 may determine that the blower 204 is on when the voltage is greater than a predetermined voltage or when a change in voltage of at least a predetermined change occurs.

Additionally or alternatively, a power sensor may measure a power consumption of the electric motor of the blower 204. The control module 130 may determine that the blower 204 is on when the power consumption is greater than a predetermined power.

Additionally or alternatively, a speed sensor may measure a rotational speed of the electric motor of the blower 204. The control module 130 may determine that the blower 204 is on when the speed is greater than a predetermined speed.

A burner 213 burns gas (e.g., natural gas or propane) to generate heat. While an example arrangement of the blower 204, the burner 213, and the evaporator 108 are provided, the present application is also applicable to other arrangements.

Additionally or alternatively, one or more sensors may be implemented downstream of the evaporator 108. For example, a pressure sensor 216 may measure a pressure of air downstream of the evaporator 108 (e.g., in a supply air duct). The control module 130 may determine that the blower 204 is on when the pressure is greater than a predetermined pressure (e.g., a barometric pressure). The pressure may approach barometric pressure when the blower 204 is off. The pressure may increase relative to barometric pressure when the blower 204 is on.

Additionally or alternatively, a temperature sensor 220 may measure a temperature of air downstream of the evaporator 108 (e.g., in a supply air duct). The control module 130 may determine that the blower 204 is on when the temperature is greater than a predetermined temperature (e.g., a setpoint temperature of the thermostat) during heating or less than the predetermined temperature during cooling. The temperature measured by the temperature sensor 220 may be an ambient temperature while the blower 204 is off.

Additionally or alternatively, a relative humidity sensor 224 may measure a relative humidity (RH) of air downstream of the evaporator 108 (e.g., in a supply air duct). The control module 130 may determine that the blower 204 is on when the relative humidity is greater than or less than a predetermined relative humidity. Different predetermined relative humidities may be used for heating mode and cooling mode. The relative humidity measured by the relative humidity sensor 224 may be an ambient relative humidity while the blower 204 is off.

Additionally or alternatively, an air flowrate (e.g., mass air flowrate (MAF)) sensor 228 may measure a flowrate (e.g., a mass flowrate) of air downstream of the evaporator 108 (e.g., in a supply air duct). The control module 130 may determine that the blower 204 is on when the air flowrate is greater than a predetermined air flowrate.

Additionally or alternatively, an anemometer 232 may measure an air speed through the ducts, such as downstream of the blower 204. The control module 130 may determine that the blower 204 is on when the air speed is greater than a predetermined speed.

Additionally or alternatively, a differential pressure sensor 236 may measure a pressure difference between (a) an air pressure within the duct and (b) an air pressure within the building outside of the duct. The control module 130 may determine that the blower 204 is on when the pressure difference (e.g., a magnitude) is greater than a predetermined value.

While example locations of sensors are provided in FIG. 2, the sensors may be located in other suitable locations, such as upstream of the evaporator 108 or upstream of the blower 204. Additionally, one or more of the sensors of FIG. 2 may be omitted or duplicated.

FIG. 3 is a functional block diagram of an example implementation of the control module 130. A compressor control module 304 controls operation of the compressor 102. For example, the compressor control module 304 may turn on the compressor 102 in response to receipt of a command (e.g., cool mode command) from a thermostat 308. The thermostat 308 may generate the command, for example, when a temperature of air within the building is greater than a setpoint temperature (in the example of cooling) or less than the setpoint temperature (in the example of heating). The compressor control module 304 may vary a speed and/or capacity of the compressor 102 when the compressor 102 is on. The compressor control module 304 may turn the compressor 102 off when the thermostat 308 stops generating the command.

A fan control module 312 controls operation of the condenser fan 316. The condenser fan 316 increases airflow past the condenser 104 when the condenser fan 316 is on. For example, the fan control module 312 may turn on the condenser fan 316 in response to receipt of the command from the thermostat 308. The fan control module 312 may turn the condenser fan 316 off when the thermostat 308 stops generating the command. In various implementations, the fan control module 312 may turn the condenser fan 316 on before the compressor 102 is turned on and maintain the condenser fan 316 on for a predetermined period after the compressor 102 is turned off.

A blower control module 320 controls operation of the blower 204. For example, the blower control module 320 may turn on the blower 204 in response to receipt of the command from the thermostat 308. The blower control module 320 may also turn on the blower 204 in response to receipt of a command for heating from the thermostat 308. The blower control module 320 may also turn on the blower 204 in response to receipt of a command to turn the blower 204 on (Fan On command) from the thermostat 308. The blower control module 320 may turn the blower 204 off when the thermostat 308 is not generating any of the commands. In various implementations, the blower control module 320 may turn the blower 204 on before the compressor 102 is turned on and maintain the blower 204 on for a predetermined period after the compressor 102 is turned off. In various implementations, the blower 204 may be a multi-speed blower and be configured to operate at multiple different speeds.

The blower control module 320 may also turn the blower 204 on when a refrigerant leak is detected using the refrigerant leak sensor 140. For example, a leak module 324 may determine that a refrigerant leak is present in the refrigeration system when the amount of refrigerant measured In proximity to (and outside of refrigerant containing components of) the refrigeration system by the refrigerant leak sensor 140 is greater than a predetermined amount. The leak module 324 may determine that a refrigerant leak is not present when the amount is less than the predetermined amount.

One or more other remedial actions may be taken when a refrigerant leak is present in the refrigeration system, such as described above. For example, the compressor control module 304 may turn the compressor 102 off and maintain the compressor 102 off for a predetermined period when a refrigerant leak is present. One or more isolation valves may also be closed, such as to pump refrigerant out from within the building and to trap the refrigerant outside of the building.

A disabling module 328 may disable the refrigerant leak sensor 140 when the blower 204 is on. The disabling module 328 may disable the refrigerant leak sensor 140, for example, by disconnecting the refrigerant leak sensor 140 from power. Disabling the refrigerant leak sensor 140 may decrease power consumption. In various implementations, the disabling module 328 may disable the leak module 324 when the blower 204 is on. This may, for example, disable detection of refrigerant leaks while the blower 204 is on.

When the blower 204 transitions from off to on, one or more operating parameters measured by one or more other sensors 332 should change. Examples of the other sensors 332 include the temperature sensor 220, the relative humidity sensor 224, the pressure sensor 216, the current sensor 208, the voltage sensor 212, the MAF sensor 228, the anemometer 232, the differential pressure sensor 236, and/or one or more other types of sensors

A verification module 336 verifies whether the blower 204 actually transitioned from OFF to ON based on one or more parameters measured by one or more of the other sensors 332. For example, the verification module 336 may determines that the blower 204 transitioned from OFF to ON when a parameter changes by at least a predetermined (threshold) amount within a predetermined period after the blower control module 320 commanded or turned the blower 204 on. Examples are discussed in detail below.

The predetermined amount(s) may be variable or fixed. In the example of the predetermined amount(s) being variable, a thresholds module 340 may set the predetermined (threshold) amount(s), as discussed further below.

The blower 204 failing to transition from OFF to ON is indicative of a fault, such as in the blower 204, the control module 130, a power source, and/or in one or more other components. If the blower 204 cannot turn on, mitigation of a refrigerant leak may not be possible. If the blower 204 fails to transition from OFF to ON, the verification module 336 indicates the presence of the fault via one or more output devices 344. For example, the verification module 336 may generate a visible indicator of the fault, such as by illuminating a fault indicator light or displaying a predetermined fault message, such as on the thermostat 308. Additionally or alternatively, the verification module 336 may generate an audible indicator of the fault, such as by generating one or more sounds via one or more speakers. Additionally or alternatively, the verification module 336 may communicate a message indicative of the fault to an account (e.g., an email address, a cellular phone number, etc.) associated with the building of the refrigeration system. The verification module 336 may communicate the message via one or more networks, such as the Internet. One or more other remedial actions may also be taken, such as disabling the compressor 102.

FIG. 4 is a flowchart depicting an example method of determining whether the blower 204 turned on. Control begins with 404 where the verification module 336 receives the pressure measured by the pressure sensor 216. As described above, the pressure sensor 216 may be located downstream of the blower 204 as illustrated in the example of FIG. 2 or upstream of the blower 204.

At 408, the verification module 336 determines whether the blower control module 320 has commanded the blower 204 to be on, applied power to the blower 204, another suitable command to turn on the blower 204 has been received. If 408 is true, control continues with 412. If 408 is false, control may return to 404.

At 412, the verification module 336 may store the last pressure measured by the pressure sensor 216 before the blower 204 was to be transitioned to ON as an initial pressure. The verification module 336 may also reset a timer, such as to zero, at 412. At 416, the verification module 336 increments the timer (e.g., timer value=timer value+1). The timer therefore tracks the period since the blower 204 was to be turned on.

At 420, the verification module 336 determines whether the timer value corresponds to greater than or equal to a predetermined period (e.g., is greater than or equal to a predetermined value). If 420 is true, control continues with 424. If 424 is false, control returns to 416. While the example of resetting the timer to zero, incrementing the timer, and determining whether the timer is greater than a predetermined period is provided, the present application is also applicable to resetting the timer corresponding to a predetermined period, decrementing the timer, and determining whether the timer is less than or equal to zero. The predetermined period may be calibratable and may be, for example, approximately 5 seconds or another suitable period.

At 424, the verification module 336 determines a pressure change based on a difference between the present pressure measured by the pressure sensor 216 and the initial pressure. The verification module 336 may set the pressure change, for example, based on or equal to the present pressure minus the initial pressure or the initial pressure minus the present pressure. The initial pressure should be approximately ambient pressure as the pressure measured by the pressure sensor 216 should be approximately equal to ambient pressure when the blower 204 is off. If the pressure sensor 216 is downstream of the blower 204, the pressure measured by the pressure sensor 216 will increase relative to the initial pressure if the blower 204 is ON. If the pressure sensor 216 is upstream of the blower 204, the pressure measured by the pressure sensor 216 will decrease relative to the initial pressure if the blower 204 is ON.

At 428, the verification module 336 determines whether the pressure change (e.g., the magnitude of the pressure change) is greater than a predetermined value (pressure). If 428 is true, the verification module 336 indicates that the blower 204 is on and/or that no fault in the blower 204 is present at 436. If 428 is false, the verification module 336 indicates that a fault is present at 432. One or more remedial actions may be taken when the fault is present. For example, the verification module 336 may disable the compressor control module 304 to prevent turning on of the compressor 102 and/or indicate the presence of the fault via the one or more output devices 344. Additionally or alternatively, the verification module 336 may close one or more isolation valves to isolate the refrigerant outside of the building when the fault is present. While the example of FIG. 4 is illustrated as ending, control may return to 404.

The thresholds module 340 may set the predetermined pressure to a fixed pressure. The fixed predetermined pressure may be a fixed value. For example only, the predetermined pressure may be approximately 1 hectopascal (hPa) or another suitable value for a transition from OFF to ON. In various implementations, the thresholds module 340 may vary the predetermined pressure. For example, the thresholds module 340 may set the predetermined pressure based on an average of the pressure changes (e.g., from 424) determined the last X times that the blower 204 transitioned from OFF to ON, where X is an integer greater than one. The thresholds module 340 may, for example, set the predetermined pressure based on or equal to the average minus a predetermined amount (e.g., 0.2 hPa). The thresholds module 340 may determine the average by summing the X pressure changes and dividing by X. FIG. 10 includes an example graph of pressure changes over time when the blower 204 turned ON and OFF.

Similar strategies to the example of FIG. 4 can be applied to other operating parameters to determine whether the blower 204 turned on. For example, FIG. 5 is a flowchart depicting an example method of determining whether the blower 204 turned on. Control begins with 504 where the verification module 336 receives the temperature measured by the temperature sensor 220. As described above, the temperature sensor 220 may be located downstream of the blower 204 as illustrated in the example of FIG. 2 or upstream of the blower 204.

At 508, the verification module 336 determines whether the blower control module 320 has commanded the blower 204 to be on, applied power to the blower 204, another suitable command to turn on the blower 204 has been received. If 508 is true, control continues with 512. If 508 is false, control may return to 504.

At 512, the verification module 336 may store the last temperature measured by the temperature sensor 220 before the blower 204 was to be transitioned to ON as an initial temperature. The verification module 336 may also reset a timer, such as to zero, at 512. At 516, the verification module 336 increments the timer (e.g., timer value=timer value+1). The timer therefore tracks the period since the blower 204 was to be turned on.

At 520, the verification module 336 determines whether the timer value corresponds to greater than or equal to a predetermined period (e.g., is greater than or equal to a predetermined value). If 520 is true, control continues with 524. If 524 is false, control returns to 516. While the example of resetting the timer to zero, incrementing the timer, and determining whether the timer is greater than a predetermined period is provided, the present application is also applicable to resetting the timer corresponding to a predetermined period, decrementing the timer, and determining whether the timer is less than or equal to zero. The predetermined period may be calibratable and may be, for example, approximately 7 seconds or another suitable period. The predetermined period used in FIG. 5 may be longer than the predetermined period used in FIG. 4.

At 524, the verification module 336 determines a temperature change based on a difference between the present temperature measured by the temperature sensor 220 and the initial temperature. The verification module 336 may set the temperature change, for example, based on or equal to the present temperature minus the initial temperature or the initial temperature minus the present temperature. The initial temperature should be approximately ambient temperature as the temperature measured by the temperature sensor 220 should be approximately equal to ambient temperature when the blower 204 is off. During operation of the refrigeration system in cooling mode (to cool the air within the building), the temperature measured by the temperature sensor 220 will decrease relative to the initial temperature if the blower 204 is ON. During operation of the refrigeration system in heating mode (to heat the air within the building), the temperature measured by the temperature sensor 220 will increase relative to the initial temperature if the blower 204 is ON.

At 528, the verification module 336 determines whether the temperature change (e.g., the magnitude of the temperature change) is greater than a predetermined value (temperature). If 528 is true, the verification module 336 indicates that the blower 204 is ON and/or that no fault in the blower 204 is present at 536. If 528 is false, the verification module 336 indicates that a fault is present at 532. One or more remedial actions may be taken when the fault is present. For example, the verification module 336 may disable the compressor control module 304 to prevent turning on of the compressor 102 and/or indicate the presence of the fault via the one or more output devices 344. Additionally or alternatively, the verification module 336 may close one or more isolation valves to isolate the refrigerant outside of the building when the fault is present. While the example of FIG. 5 is illustrated as ending, control may return to 504.

The thresholds module 340 may set the predetermined temperature to a fixed temperature (e.g. one predetermined temperature for heating mode and one predetermined temperature for cooling mode). For example only, the predetermined temperature may be approximately 9 degrees Celsius or another suitable value for cooling mode. In various implementations, the thresholds module 340 may vary the predetermined temperature. For example, the thresholds module 340 may set the predetermined temperature based on an average of the temperature changes (e.g., from 524) determined the last X times that the blower 204 transitioned from OFF to ON, where X is an integer greater than one. The thresholds module 340 may, for example, set the predetermined temperature based on or equal to the average minus a predetermined amount (e.g., 1 degree Celsius). The thresholds module 340 may determine the average by summing the X temperature changes and dividing by X. FIG. 11 includes an example graph of temperature changes over time when the blower 204 turned ON and OFF during cooling mode operation. The temperature may move oppositely—decrease when the blower 204 turns OFF and increase when the blower 204 turns ON—during heating mode operation.

As another example, FIG. 6 is a flowchart depicting an example method of determining whether the blower 204 turned on. Control begins with 604 where the verification module 336 receives the relative humidity measured by the humidity sensor 224. As described above, the humidity sensor 224 may be located downstream of the blower 204 as illustrated in the example of FIG. 2 or upstream of the blower 204.

At 608, the verification module 336 determines whether the blower control module 320 has commanded the blower 204 to be on, applied power to the blower 204, another suitable command to turn on the blower 204 has been received. If 608 is true, control continues with 612. If 608 is false, control may return to 604.

At 612, the verification module 336 may store the last humidity measured by the humidity sensor 224 before the blower 204 was to be transitioned to ON as an initial humidity. The verification module 336 may also reset a timer, such as to zero, at 612. At 616, the verification module 336 increments the timer (e.g., timer value=timer value+1). The timer therefore tracks the period since the blower 204 was to be turned on.

At 620, the verification module 336 determines whether the timer value corresponds to greater than or equal to a predetermined period (e.g., is greater than or equal to a predetermined value). If 620 is true, control continues with 624. If 624 is false, control returns to 616. While the example of resetting the timer to zero, incrementing the timer, and determining whether the timer is greater than a predetermined period is provided, the present application is also applicable to resetting the timer corresponding to a predetermined period, decrementing the timer, and determining whether the timer is less than or equal to zero. The predetermined period may be calibratable and may be, for example, approximately 8 seconds or another suitable period. The predetermined period used in FIG. 6 may be longer than the predetermined period used in FIG. 4.

At 624, the verification module 336 determines a humidity change based on a difference between the present humidity measured by the humidity sensor 224 and the initial humidity. The verification module 336 may set the (relative) humidity change, for example, based on or equal to the present humidity minus the initial humidity or the initial humidity minus the present humidity. The initial humidity should be approximately ambient humidity as the relative humidity measured by the humidity sensor 224 should be approximately equal to ambient humidity when the blower 204 is off. During operation of the refrigeration system in cooling mode, if the humidity sensor 224 is downstream of the evaporator 108, the relative humidity measured by the humidity sensor 224 will increase (via moisture from the evaporator 108) relative to the initial humidity if the blower 204 is ON. During operation of the refrigeration system in heating mode, the relative humidity measured by the humidity sensor 224 will decrease relative to the initial humidity if the blower 204 is ON.

At 628, the verification module 336 determines whether the humidity change (e.g., the magnitude of the humidity change) is greater than a predetermined value (humidity). If 628 is true, the verification module 336 indicates that the blower 204 is ON and/or that no fault in the blower 204 is present at 636. If 628 is false, the verification module 336 indicates that a fault is present at 632. One or more remedial actions may be taken when the fault is present. For example, the verification module 336 may disable the compressor control module 304 to prevent turning on of the compressor 102 and/or indicate the presence of the fault via the one or more output devices 344. Additionally or alternatively, the verification module 336 may close one or more isolation valves to isolate the refrigerant outside of the building when the fault is present. While the example of FIG. 6 is illustrated as ending, control may return to 604.

The thresholds module 340 may set the predetermined humidity to a fixed humidity (e.g. one predetermined humidity for heating mode and one predetermined humidity for cooling mode). For example only, the predetermined humidity may be approximately 1 gram per cubic meter or another suitable value. In various implementations, the thresholds module 340 may vary the predetermined humidity. For example, the thresholds module 340 may set the predetermined humidity based on an average of the humidity changes (e.g., from 624) determined the last X times that the blower 204 transitioned from OFF to ON, where X is an integer greater than one. The thresholds module 340 may, for example, set the predetermined humidity based on or equal to the average minus a predetermined amount (e.g., 0.2 grams per cubic meter). The thresholds module 340 may determine the average by summing the X humidity changes and dividing by X.

The thresholds module 340 may also adjust the predetermined humidity based on the initial humidity. For example, the thresholds module 340 may increase the predetermined humidity (e.g., above the average) as the initial humidity increases. The thresholds module 340 may decrease the predetermined humidity (e.g., below the average) as the initial humidity decrease.

As another example, FIG. 7 is a flowchart depicting an example method of determining whether the blower 204 turned on. Control begins with 704 where the verification module 336 receives a gas flowrate, such as the mass air flowrate measured by the MAF sensor 228 or the gas flowrate measured by the gas flowrate sensor 214. As described above, the MAF sensor 228 may be located downstream of the blower 204 as illustrated in the example of FIG. 2 or upstream of the blower 204.

At 708, the verification module 336 determines whether the blower control module 320 has commanded the blower 204 to be on, applied power to the blower 204, another suitable command to turn on the blower 204 has been received. If 708 is true, control continues with 712. If 708 is false, control may return to 704.

At 712, the verification module 336 may store the last gas flowrate measured by the gas flowrate sensor before the blower 204 was to be transitioned to ON as an initial gas flowrate. The verification module 336 may also reset a timer, such as to zero, at 712. At 716, the verification module 336 increments the timer (e.g., timer value=timer value+1). The timer therefore tracks the period since the blower 204 was to be turned on.

At 720, the verification module 336 determines whether the timer value corresponds to greater than or equal to a predetermined period (e.g., is greater than or equal to a predetermined value). If 720 is true, control continues with 724. If 724 is false, control returns to 716. While the example of resetting the timer to zero, incrementing the timer, and determining whether the timer is greater than a predetermined period is provided, the present application is also applicable to resetting the timer corresponding to a predetermined period, decrementing the timer, and determining whether the timer is less than or equal to zero. The predetermined period may be calibratable and may be, for example, approximately 8 seconds or another suitable period. The predetermined period used in FIG. 7 may be shorter than the predetermined period used in FIG. 4.

At 724, the verification module 336 determines a gas flowrate change based on a difference between the present gas flowrate measured by the gas flowrate sensor and the initial gas flowrate. The verification module 336 may set the gas flowrate change, for example, based on or equal to the present gas flowrate minus the initial gas flowrate or the initial gas flowrate minus the present gas flowrate. The initial gas flowrate should be approximately zero when the blower 204 is OFF. The gas flowrate measured by the gas flowrate sensor will increase relative to the initial gas flowrate if the blower 204 is ON.

At 728, the verification module 336 determines whether the gas flowrate change (e.g., the magnitude of the gas flowrate change) is greater than a predetermined value (flowrate). If 728 is true, the verification module 336 indicates that the blower 204 is ON and/or that no fault in the blower 204 is present at 736. If 728 is false, the verification module 336 indicates that a fault is present at 732. One or more remedial actions may be taken when the fault is present. For example, the verification module 336 may disable the compressor control module 304 to prevent turning on of the compressor 102 and/or indicate the presence of the fault via the one or more output devices 344. Additionally or alternatively, the verification module 336 may close one or more isolation valves to isolate the refrigerant outside of the building when the fault is present. While the example of FIG. 7 is illustrated as ending, control may return to 704.

The thresholds module 340 may set the predetermined gas flowrate to a fixed gas flowrate. For example only, the predetermined gas flowrate may be approximately 1 gram per second or another suitable mass per unit of time. In various implementations, the thresholds module 340 may vary the predetermined gas flowrate. For example, the thresholds module 340 may set the predetermined gas flowrate based on an average of the gas flowrate changes (e.g., from 724) determined the last X times that the blower 204 transitioned from OFF to ON, where X is an integer greater than one. The thresholds module 340 may, for example, set the predetermined gas flowrate based on or equal to the average minus a predetermined amount (e.g., 0.2 grams per second). The thresholds module 340 may determine the average by summing the X gas flowrate changes and dividing by X.

As another example, FIG. 8 is a flowchart depicting an example method of determining whether the blower 204 turned on. Control begins with 804 where the verification module 336 receives the current measured by the current sensor 208.

At 808, the verification module 336 determines whether the blower control module 320 has commanded the blower 204 to be on, applied power to the blower 204, another suitable command to turn on the blower 204 has been received. If 808 is true, control continues with 812. If 808 is false, control may return to 804.

At 812, the verification module 336 may store the last current measured by the current sensor 208 before the blower 204 was to be transitioned to ON as an initial current. The verification module 336 may also reset a timer, such as to zero, at 812. At 816, the verification module 336 increments the timer (e.g., timer value=timer value+1). The timer therefore tracks the period since the blower 204 was to be turned on.

At 820, the verification module 336 determines whether the timer value corresponds to greater than or equal to a predetermined period (e.g., is greater than or equal to a predetermined value). If 820 is true, control continues with 824. If 824 is false, control returns to 816. While the example of resetting the timer to zero, incrementing the timer, and determining whether the timer is greater than a predetermined period is provided, the present application is also applicable to resetting the timer corresponding to a predetermined period, decrementing the timer, and determining whether the timer is less than or equal to zero. The predetermined period may be calibratable and may be, for example, approximately 8 seconds or another suitable period. The predetermined period used in FIG. 8 may be shorter than the predetermined period used in FIG. 4.

At 824, the verification module 336 determines a current change based on a difference between the present current measured by the current sensor 208 and the initial current. The verification module 336 may set the current change, for example, based on or equal to the present current minus the initial current or the initial current minus the present current. The initial current may be approximately zero when the blower 204 is off.

At 828, the verification module 336 determines whether the current change (e.g., the magnitude of the current change) is greater than a predetermined value (current). If 828 is true, the verification module 336 indicates that the blower 204 is ON and/or that no fault in the blower 204 is present at 836. If 828 is false, the verification module 336 indicates that a fault is present at 832. One or more remedial actions may be taken when the fault is present. For example, the verification module 336 may disable the compressor control module 304 to prevent turning on of the compressor 102 and/or indicate the presence of the fault via the one or more output devices 344. Additionally or alternatively, the verification module 336 may close one or more isolation valves to isolate the refrigerant outside of the building when the fault is present. While the example of FIG. 8 is illustrated as ending, control may return to 804.

The thresholds module 340 may set the predetermined current to a fixed current. For example only, the predetermined current may be approximately 5 amps or another suitable value. In various implementations, the thresholds module 340 may vary the predetermined current. For example, the thresholds module 340 may set the predetermined current based on an average of the current changes (e.g., from 824) determined the last X times that the blower 204 transitioned from OFF to ON, where X is an integer greater than one. The thresholds module 340 may, for example, set the predetermined current based on or equal to the average minus a predetermined amount (e.g., 0.2 amps). The thresholds module 340 may determine the average by summing the X current changes and dividing by X.

As another example, FIG. 9 is a flowchart depicting an example method of determining whether the blower 204 turned on. Control begins with 904 where the verification module 336 receives the voltage measured by the voltage sensor 212.

At 908, the verification module 336 determines whether the blower control module 320 has commanded the blower 204 to be on, applied power to the blower 204, another suitable command to turn on the blower 204 has been received. If 908 is true, control continues with 912. If 908 is false, control may return to 904.

At 912, the verification module 336 may store the last voltage measured by the voltage sensor 212 before the blower 204 was to be transitioned to ON as an initial current. The verification module 336 may also reset a timer, such as to zero, at 912. At 916, the verification module 336 increments the timer (e.g., timer value=timer value+1). The timer therefore tracks the period since the blower 204 was to be turned on.

At 920, the verification module 336 determines whether the timer value corresponds to greater than or equal to a predetermined period (e.g., is greater than or equal to a predetermined value). If 920 is true, control continues with 924. If 924 is false, control returns to 916. While the example of resetting the timer to zero, incrementing the timer, and determining whether the timer is greater than a predetermined period is provided, the present application is also applicable to resetting the timer corresponding to a predetermined period, decrementing the timer, and determining whether the timer is less than or equal to zero. The predetermined period may be calibratable and may be, for example, approximately 8 seconds or another suitable period. The predetermined period used in FIG. 9 may be shorter than the predetermined period used in FIG. 4.

At 924, the verification module 336 determines a voltage change based on a difference between the present voltage measured by the voltage sensor 212 and the initial voltage. The verification module 336 may set the voltage change, for example, based on or equal to the present voltage minus the initial voltage or the initial voltage minus the present voltage. The initial voltage may be approximately zero when the blower 204 is off.

At 928, the verification module 336 determines whether the voltage change (e.g., the magnitude of the voltage change) is greater than a predetermined value (current). If 928 is true, the verification module 336 indicates that the blower 204 is ON and/or that no fault in the blower 204 is present at 936. If 928 is false, the verification module 336 indicates that a fault is present at 932. One or more remedial actions may be taken when the fault is present. For example, the verification module 336 may disable the compressor control module 304 to prevent turning on of the compressor 102 and/or indicate the presence of the fault via the one or more output devices 344. Additionally or alternatively, the verification module 336 may close one or more isolation valves to isolate the refrigerant outside of the building when the fault is present. While the example of FIG. 9 is illustrated as ending, control may return to 904.

The thresholds module 340 may set the predetermined voltage to a fixed voltage. For example only, the predetermined voltage may be approximately 5 volts or another suitable value. In various implementations, the thresholds module 340 may vary the predetermined voltage. For example, the thresholds module 340 may set the predetermined voltage based on an average of the voltage changes (e.g., from 924) determined the last X times that the blower 204 transitioned from OFF to ON, where X is an integer greater than one. The thresholds module 340 may, for example, set the predetermined voltage based on or equal to the average minus a predetermined amount (e.g., 0.2 volts). The thresholds module 340 may determine the average by summing the X voltage changes and dividing by X.

While the examples of FIGS. 4-9 are shown separately, the examples of FIGS. 4-9 may be combined. For example, the example, the verification module 336 may indicate that the blower 204 is ON and/or that no fault in the blower 204 is present when all of 428, 528, 628, 728, 828, and 928 are true. The verification module 336 may indicate that a fault is present when at least one of 428, 528, 628, 728, 828, and 928 is false.

Also, while the examples of humidity, pressure, temperature, gas flow, current, and voltage have been provided, the above is also applicable to wind speed (e.g., see FIG. 12) and pressure difference (e.g., see FIG. 13).

Also, while the above is discussed in terms of the blower 204 being on, the present application is also applicable to other mitigation devices. For example, the above may also be applicable to an actuation of an isolation valve, an economizer of the building (e.g., a whole home economizer), an electronic expansion valve, and a refrigeration case fan. The blower 204 and other types of mitigation devices may be more generally referred to as mitigation devices.

Also, while the above has been discussed in terms of the blower 204 turning on, the above is also applicable to the blower 204 transitioning from a lower speed to a higher speed. The verification module 336 may verify and indicate whether the blower 204 transitioned from the lower speed to the higher speed using the above (e.g., FIGS. 4-9). In the example of transitioning from one speed to another speed, the thresholds module may set the threshold, for example, based on speed change.

FIG. 14 is a flowchart depicting an example method of determining whether an expected state of a mitigation device matches a current state of the mitigation device. Control begins with 1404 where the verification module 336 receives a parameter measured by one of the other sensors 332, and stores the parameter. Examples of the parameter include temperature, pressure, relative humidity, gas flowrate, current, voltage, speed (of the motor of the blower 204), wind speed, and pressure difference.

At 1408, the verification module 336 obtains the stored value of the parameter from a predetermined period before the present time (or control loop). For example, the parameters may be stored by the verification module 336 with time stamps, and the verification module 336 may determine the time stamp corresponding to the predetermined period before the present time.

At 1412, the verification module 336 may determine a change in the parameter of the predetermined period based on the present value of the parameter (from 1404) and the stored value of the parameter from the predetermined period earlier. The verification module 336 may set the change, for example, based on or equal to the parameter minus the stored value or vice versa.

At 1416, the verification module 336 may determine whether the change is greater than a predetermined value. The thresholds module 340 may set the predetermined value to a fixed value or vary the predetermined value, such as described above. The thresholds module 340 may set the predetermined value, for example, based on the current state (e.g., ON or OFF or speed) of the mitigation device (e.g., the blower 204). If 1416 is true, at 1420 the verification module 336 updates the current (present) state of the mitigation device, such as to ON, OFF, or a present speed of the mitigation device. If 1416 is false, at 1424, the verification module 336 leaves the current state of the mitigation device unchanged. In this manner, the verification module 336 updates the state of the mitigation device when a suitable change in the parameter occurs over a period.

At 1428, the verification module 336 determines whether the current state of the mitigation device is the same an expected current state of the mitigation device. The verification module 336 may determine the expected current state, for example, based on the output of control module that controls that mitigation device, such as the blower control module 320 in the example of the mitigation device being the blower 204. If 1428 is true, the verification module 336 may reset a timer at 1432 and control may continue with 1440. If 1428 is false, the verification module 336 may increment the timer at 1436 (e.g., timer=timer+1), and control may continue with 1440.

At 1440, the verification module 336 may determine whether the timer value corresponds to greater than or equal to a predetermined period (e.g., is greater than or equal to a predetermined value). If 1440 is true, the verification module 336 indicates that no fault is present at 1444, and control may return to 1404. If 1440 is false, the verification module 336 may indicate that a fault is present with the mitigation device at 1448, and control may return to 1404. In this manner, the verification module 336 may require that the current state be different than the expected current state for longer than the predetermined period before indicating that a fault has occurred. While the example of resetting the timer to zero, incrementing the timer, and determining whether the timer is greater than a predetermined period is provided, the present application is also applicable to resetting the timer corresponding to a predetermined period, decrementing the timer, and determining whether the timer is less than or equal to zero. The predetermined period may be calibratable and may be longer than the period used at 1408.

The foregoing description is merely illustrative in nature and is in no way intended to limit the disclosure, its application, or uses. The broad teachings of the disclosure can be implemented in a variety of forms. Therefore, while this disclosure includes particular examples, the true scope of the disclosure should not be so limited since other modifications will become apparent upon a study of the drawings, the specification, and the following claims. It should be understood that one or more steps within a method may be executed in different order (or concurrently) without altering the principles of the present disclosure. Further, although each of the embodiments is described above as having certain features, any one or more of those features described with respect to any embodiment of the disclosure can be implemented in and/or combined with features of any of the other embodiments, even if that combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and permutations of one or more embodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example, between modules, circuit elements, semiconductor layers, etc.) are described using various terms, including “connected,” “engaged,” “coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and “disposed.” Unless explicitly described as being “direct,” when a relationship between first and second elements is described in the above disclosure, that relationship can be a direct relationship where no other intervening elements are present between the first and second elements, but can also be an indirect relationship where one or more intervening elements are present (either spatially or functionally) between the first and second elements. As used herein, the phrase at least one of A, B, and C should be construed to mean a logical (A OR B OR C), using a non-exclusive logical OR, and should not be construed to mean “at least one of A, at least one of B, and at least one of C.”

In the figures, the direction of an arrow, as indicated by the arrowhead, generally demonstrates the flow of information (such as data or instructions) that is of interest to the illustration. For example, when element A and element B exchange a variety of information but information transmitted from element A to element B is relevant to the illustration, the arrow may point from element A to element B. This unidirectional arrow does not imply that no other information is transmitted from element B to element A. Further, for information sent from element A to element B, element B may send requests for, or receipt acknowledgements of, the information to element A.

In this application, including the definitions below, the term “module” or the term “controller” may be replaced with the term “circuit.” The term “module” may refer to, be part of, or include: an Application Specific Integrated Circuit (ASIC); a digital, analog, or mixed analog/digital discrete circuit; a digital, analog, or mixed analog/digital integrated circuit; a combinational logic circuit; a field programmable gate array (FPGA); a processor circuit (shared, dedicated, or group) that executes code; a memory circuit (shared, dedicated, or group) that stores code executed by the processor circuit; other suitable hardware components that provide the described functionality; or a combination of some or all of the above, such as in a system-on-chip.

The module may include one or more interface circuits. In some examples, the interface circuits may include wired or wireless interfaces that are connected to a local area network (LAN), the Internet, a wide area network (WAN), or combinations thereof. The functionality of any given module of the present disclosure may be distributed among multiple modules that are connected via interface circuits. For example, multiple modules may allow load balancing. In a further example, a server (also known as remote, or cloud) module may accomplish some functionality on behalf of a client module.

The term code, as used above, may include software, firmware, and/or microcode, and may refer to programs, routines, functions, classes, data structures, and/or objects. The term shared processor circuit encompasses a single processor circuit that executes some or all code from multiple modules. The term group processor circuit encompasses a processor circuit that, in combination with additional processor circuits, executes some or all code from one or more modules. References to multiple processor circuits encompass multiple processor circuits on discrete dies, multiple processor circuits on a single die, multiple cores of a single processor circuit, multiple threads of a single processor circuit, or a combination of the above. The term shared memory circuit encompasses a single memory circuit that stores some or all code from multiple modules. The term group memory circuit encompasses a memory circuit that, in combination with additional memories, stores some or all code from one or more modules.

The term memory circuit is a subset of the term computer-readable medium. The term computer-readable medium, as used herein, does not encompass transitory electrical or electromagnetic signals propagating through a medium (such as on a carrier wave); the term computer-readable medium may therefore be considered tangible and non-transitory. Non-limiting examples of a non-transitory, tangible computer-readable medium are nonvolatile memory circuits (such as a flash memory circuit, an erasable programmable read-only memory circuit, or a mask read-only memory circuit), volatile memory circuits (such as a static random access memory circuit or a dynamic random access memory circuit), magnetic storage media (such as an analog or digital magnetic tape or a hard disk drive), and optical storage media (such as a CD, a DVD, or a Blu-ray Disc).

The apparatuses and methods described in this application may be partially or fully implemented by a special purpose computer created by configuring a general purpose computer to execute one or more particular functions embodied in computer programs. The functional blocks, flowchart components, and other elements described above serve as software specifications, which can be translated into the computer programs by the routine work of a skilled technician or programmer.

The computer programs include processor-executable instructions that are stored on at least one non-transitory, tangible computer-readable medium. The computer programs may also include or rely on stored data. The computer programs may encompass a basic input/output system (BIOS) that interacts with hardware of the special purpose computer, device drivers that interact with particular devices of the special purpose computer, one or more operating systems, user applications, background services, background applications, etc.

The computer programs may include: (i) descriptive text to be parsed, such as HTML (hypertext markup language), XML (extensible markup language), or JSON (JavaScript Object Notation) (ii) assembly code, (iii) object code generated from source code by a compiler, (iv) source code for execution by an interpreter, (v) source code for compilation and execution by a just-in-time compiler, etc. As examples only, source code may be written using syntax from languages including C, C++, C #, Objective-C, Swift, Haskell, Go, SQL, R, Lisp, Java®, Fortran, Perl, Pascal, Curl, OCaml, Javascript®, HTML5 (Hypertext Markup Language 5th revision), Ada, ASP (Active Server Pages), PHP (PHP: Hypertext Preprocessor), Scala, Eiffel, Smalltalk, Erlang, Ruby, Flash®, Visual Basic®, Lua, MATLAB, SIMULINK, and Python®. 

What is claimed is:
 1. A mitigation verification system, comprising: a control module configured to selectively transition a mitigation device of a refrigeration system of a building from a first state to a second state; and a verification module configured to verify and generate an indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state based on a change in a parameter of the refrigeration system over a period in response to the transition by the control module.
 2. The mitigation verification system of claim 1 wherein the first state is an OFF state and the second state is an ON state.
 3. The mitigation verification system of claim 1 wherein the first state is a first speed and the second state is a second speed.
 4. The mitigation verification system of claim 1 wherein the mitigation device is a blower configured to increase airflow past a heat exchanger of the refrigeration system within the building.
 5. The mitigation verification system of claim 1 wherein the parameter of the refrigeration system is a temperature of air in a duct within the building measured by a temperature sensor.
 6. The mitigation verification system of claim 1 wherein the parameter of the refrigeration system is a pressure of air in a duct within the building measured by a pressure sensor.
 7. The mitigation verification system of claim 1 wherein the parameter of the refrigeration system is a flowrate of air in a duct within the building measured by a flowrate sensor.
 8. The mitigation verification system of claim 1 wherein the parameter of the refrigeration system is a humidity of air in a duct within the building measured by a humidity sensor.
 9. The mitigation verification system of claim 1 wherein the parameter of the refrigeration system is a current to a motor of a blower configured to increase airflow past a heat exchanger of the refrigeration system within the building.
 10. A system, comprising: the mitigation verification system of claim 1; and a refrigerant sensor configured to measure an amount of a refrigerant of the refrigerant system in air, wherein the verification module is configured to disable the refrigerant sensor when the mitigation device is in the ON state.
 11. The system of claim 10 wherein the refrigerant is classified as at least mildly flammable by at least one governing body.
 12. The system of claim 10 wherein the control module is configured to selectively transition the mitigation device from the first state to the second state when the amount of the amount of refrigerant of the refrigerant system in air is greater than a predetermined value.
 13. The mitigation verification system of claim 1 wherein the verification module is configured to generate the indicator that the mitigation device of the refrigeration system transitioned from the first state to the second state when a magnitude of the change in the parameter of the refrigeration system over the period is greater than a predetermined value.
 14. The mitigation verification system of claim 13 further comprising a thresholds module configured to set the predetermined value to a fixed predetermined value.
 15. The mitigation verification system of claim 13 further comprising a thresholds module configured to vary the predetermined value.
 16. The mitigation verification system of claim 13 further comprising a thresholds module configured to set the predetermined value based on an average of X values of the change measured in response to X transitions by the control module.
 17. The mitigation verification system of claim 1 wherein the verification module configured to verify and generate the indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state further based on a second change in a second parameter of the refrigeration system over a second period in response to the transition by the control module.
 18. The mitigation verification system of claim 18 wherein the verification module configured to verify and generate the indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state further based on a third change in a third parameter of the refrigeration system over a third period in response to the transition by the control module.
 19. A verification system, comprising: a control module configured to selectively transition a mitigation device of a refrigeration system of a building from a first state to a second state; and a verification module configured to: determine a change in a parameter of the refrigeration system over a predetermined period; determine whether the change is greater than a predetermined value associated with the mitigation device transitioning from the first stat to the second state; and update and indicate a present state of the mitigation device when the change is greater than the predetermined value.
 20. A verification method, comprising: selectively transitioning a mitigation device of a refrigeration system of a building from a first state to a second state; and verifying and generating an indicator of whether the mitigation device of the refrigeration system transitioned from the first state to the second state based on a change in a parameter of the refrigeration system over a period in response to the transition by the control module. 